This invention relates to sodium sulfur batteries and more particularly to methods of producing a joint between a body of beta-alumina such as a sodium sulfur cell electrolyte tube and a body of alpha-alumina such as an insulating ring for the electrolyte tube with a glass bonding agent.
Sodium sulfur batteries are known. The known characteristic of sodium sulfur batteries is that they provide a highly desirable power output to weight ratio. The known disadvantage of sodium sulfur batteries is that they are difficult to manufacture economically so as to operate with any high degree of reliability. If the joint between the electrolyte tube and the insulating ring for the tube of the sodium sulfur cell fails, the cell itself is essentially in a fail mode. Heretofore, this joint has been produced by assembling the electrolyte tube, the insulating ring, and a ring of glass bonding agent and then subjecting the assembled elements of the joint to heat from a gas flame or electrical resistant heat source. Typically, the joint is subjected to a maximum temperature of 1100.degree. C. for a treatment period of approximately sixteen hours, a significant portion of which constitutes an annealing step. The energy consumption is substantially high both because of the magnitude of the heating step and particularly the long duration of the annealing step. There is sufficient excess cost involved in the process of producing the joint mentioned above and sufficient lack of reliability in the joint so produced as to establish a need for a economical method which will produce a more reliable joint.